code: def test_layer_from_shape(self, layer_from_shape):
      layer = layer_from_shape
      assert layer.input_layers[0] is None
      assert layer.input_shapes[0] == (None, 20)
      assert layer.input_layers[1] is not None
      assert layer.input_shapes[1] == layer.input_layers[1].output_shape
  
imports: from mock import Mock
  import numpy
  import pytest
  import theano
label_desc: Use image node_id 4 for calling the TestMergeLayer obj's underlying member method code with example usage: obj.test_layer_from_shape(layer_from_shape) without return types